Error in recording data vs time... time drifts

Discussion in 'Embedded Systems and Microcontrollers' started by CrackJack, Jan 14, 2011.

  1. CrackJack

    Thread Starter Active Member

    Aug 7, 2009
    127
    0
    Hello everyone,
    I have a weird problem. I am writing a continuous data (13hrs) in an external flash memory using Silicon Labs C8051 micro-controller. the uC is loggin acceleration data at 1000hz in unfavorable conditions (vibrations and heat). we reached upto 52 deg C, and the accelerations were around 10g.

    however, we observed that the data writing shifted with time. i mean there were some drifts in the time stamps the data was written to the flash memory as compared to our master clock. this time drift was initially few seconds, but later on increased upto 5mins.(when the battery was about to die).

    The entire ckt was powered using AA batteries (very good batteries upto 3Ah rating for 20hrs)...

    can it be possible that as the battery life goes down, the clocking of the uC with respect to the crystal drifts??? i mean, 1ms clock of the crystal may no longer be 1ms(in real time).

    please let me know... thanks
     
  2. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    This device doesn't have an RTC, so I'm curious as to how you keep track of time. MPU clocks will shift with temp, but not typically with voltage within the specs. You should do an orderly shutdown on low voltage. But even then, you should be good up till, unless your device is constantly restarting on voltage recovery.
     
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